An intraocular lens (IOL) of the type used for replacement of the natural lens of the human eye typically comprises an optic and one or more fixation members. When implanted, the optic serves as the lens of the eye, and the fixation members are used to mount or fix the optic in position within the eye.
The optic typically has anterior and posterior faces, at least one of which may be curved, and a peripheral edge, which is often cylindrical. The optic may be formed of various different materials, including polymethylmethacrylate (PMMA).
The fixation members are typically resilient, and they are attached to the optic. In some IOL's, the fixation members are formed integrally with the optic. However, in many other IOL's, the fixation members are separate members which must be attached to the optic.
One common method of attachment is to drill intersecting holes into the periphery of the optic and insert and inner end portion of the fixation member into one of the holes. A heated probe is then inserted through the other of the holes and into contact with the inner end portion of the fixation member to melt it. This causes the inner end portion of the fixation member to flow into the second hole and harden to thereby provide a mechanical interlock with the optic. This technique requires a skilled technician and is not as fast as desired in that it requires the drilling of two precision, very small diameter holes into the optic and the subsequent insertion of a very fine heated probe into one of the small-diameter holes. In addition, there is the danger that the optic will be damaged by the hot probe or from the clean-up work done on the optic following use of the hot probe.
It is also known, as shown in Chase et al U.S. Pat. No. 4,307,043, to provide a threaded bore extending between the faces of the optic and to insert the fixation member completely through the optic so that both ends of the fixation member project beyond the optic. A tool applies heat to one end of the fixation member to cause the end of the fixation member to fill the bore to attach the fixation member to the optic. This technique, although satisfactory for some applications, has the disadvantage of requiring contact between a heat-applying member and one end of the fixation member. This contact must be carried out with skill and accuracy to avoid damaging the optic.